The invention relates to electronic fuel-injection circuitry for internal-combustion engines and is more particularly concerned with generation of suitable throttle-responsive fuel-flow control signals used in such circuitry.
Reference is made to my U.S. Pat. Nos. 3,305,351 and 4,349,000 for detailed discussion of pulse-width modulating circuitry for operation of the solenoids of fuel-injectors in a variety of engines of the character indicated. The disclosure in said patents, for example in connection with FIG. 6 of said U.S. Pat. No. 4,349,000, is concerned with circuit accommodation of various input parameters, in the form of analog voltages which reflect air-mass flow for the current engine speed, and a correction is made for volumetric efficiency of the particular engine, to arrive at a pulse-width modulating voltage E.sub.MOD. in a line to each of two like square-wave pulse generators. These pulse generators respectively serve for fuel-injection control in different groups of cylinders in the involved engine. The input parameters further include engine speed and throttle setting but there is no disclosure of a particular relationship between throttle setting and the requisite electrical-signal response to throttle position.
Ordinarily, each engine will have its own optimum requirement for a fuel-flow control signal which has a particular non-linear relation to throttle position. The degree of non-linearity will depend upon engine size and the nature of power demands expected in normal use of the engine. Thus, a particular non-linearly related signal generated for one engine may not be suitable for operational requirements of another engine. As a consequence, a variety of specialpurpose position-transducer and circuit-design configurations must be available in inventory if the engine manufacturer, for example, a marine-outboard engine manufacturer, is to be able to satisfy customer demand despite the high seasonal fluctuations in such demand.